This proposed research is needed to better understand the impact of development-related communication disorders on the hearing and understanding of everyday speech. Specifically, the relationship between development and listener use of sequential acoustic and contextual clues for understanding everyday speech will be studied. Conventional isolated-word recognition measures fail to provide an effective basis for aural habilitative and rehabilitative decision-making because they do not reflect listener abilities to understand everyday speech. In everyday speech, words occur in context and in an on-going temporal sequence. Listeners must quickly percieve and process a complex interaction of acoustic and contextual clues. Previous research indicates that in everyday speech, young adult normal hearing listeners identify words as early as one half into a words' presentation. However, more research is needed to understand the process of real-time word identification in child and older adult populations. This proposed research focuses on two related long-term objectives. The first is to increase our understanding of the developmental course of real-time speech perception and processing. The second objective is to study the feasibility of employing time-gated word identification tasks to evaluate everyday real-time speech recognition abilities in child and adult populations. The proposed experiments involve the study of four age ranges (5 - 7, 8 - 10, 18 -23, and 60 - 70 years) in adult and child listeners. A gating paradigm will be developed to determine listener use of two types of preceding contexts in five time-gated word presentation conditions for word identification. The data resulting from these experiments will contribute to our understanding of developmental changes in listener use of: 1) sequential acoustic-phonetic cues, 2) preceding context, and 3) real-time integration of acoustic and contextual cues for word identification.